Interfacial Shear Rheometer

The KSV NIMA Interfacial Shear Rheometer provides an extremely sensitive method for measuring the  viscoelastic properties of films at fluid interfaces (gas/liquid and liquid/liquid). Viscoelastic properties and surface pressure can be measured simultaneously. The film packing density can also be controlled while measuring.

Features & Benefits

  • The most sensitive interfacial rheometer available—it is able to measure very weak elastic and viscous moduli of surfaces and interfaces. The high sensitivity of the method is due to fact that the low inertia hydrophobic probe is moved by magnetic field without mechanical connections. The high sensitivity is crucial in many applications, for example with experiments on fatty acids.
  • In many applications, such as with biofilms, the long-lasting chemical interactions and film creation kinetics need to be followed in real-time. KSV NIMA ISR is the most suitable instrument for the long-lasting experiments as the probe is floating at the interface, and therefore its location does not demand any adjustments to compensate the influence of evaporation.
  • The only interfacial rheometer to enable simultaneous measuring and controlling of surface pressure due to easy integration with KSV NIMA Langmuir Troughs. This makes it possible to correlate rheological data with monolayer surface pressure and phase transitions that are crucial when working with insoluble surfactants.
  • Possibility to work with low volumes down to 4.7 mL saves time and cost when working with valuable compounds and subphases.
  • Built-in data plotting option with capability of viewing multiple measurement results in one graph. Measured data can easily be exported and converted to a data file that is readable using common plotting software.

Applications

Emulsion and foam stability, bubble and micelle formation, breakage and fusion and interfacial reactions are largely affected by the rheological properties of the interface. Applications can be found in many industries. For example proteins, polymers, pigments, fluoroalkanes and other emulsifiers are strong stabilizers in dispersions and used in the pharmaceutical, cosmetic and food industries.

  • Prediction of emulsion, froth and foam stability. Viscoelasticity of an interface can predict the stability of a complex fluid. Micelle/droplet fusion and fission are largely dependent on the interface viscoelasticity.
  • Determination of thin film structure. The presence of networking, hydrogen bonding and other interactions can be detected from the viscoelastic behavior of films.
  • Examination of phase transitions. Phase transitions in a monolayer (thin film) can result in a change in the rheological properties of the layer.
  • Real-time monitoring of surface reactions. Surface gelation, network formation and protein denaturation at interfaces are detected from the changes in the viscoelastic properties at the interface.
  • Continuous monitoring of molecule adsorption into interfaces. In many biological systems the adsorption and desorption at interfaces and surfaces can change viscoelasticity. Processes in cells such as mitosis are highly dependent on membrane rheology.

Product details

The KSV NIMA ISR method is based on interfacial shear rheology. A magnetized probe positioned at the interface is used to create shear deformation on the interface which response can be measured by recording the probe movement optically.

For more information about the technology, see:

KSV NIMA ISR enables both dynamic and static measurements to define viscoelasticity of the interfacial layers. With dynamic measurement, viscoelastic properties are measured as a function of frequency, time, strain, temperature or surface pressure. Static measurement enables the creep test to be performed and indicates whether the system behaves like an ideal Newtonian liquid (dashpot model) or ideal elastic (spring model). These measurements enable the following parameters to be defined:

  • Elastic (storage) modulus, G’
  • Viscous (loss) modulus, G’’
  • Dynamic interfacial viscosity, μs*
  • Surface/interfacial viscosity, η
  • Relaxation times, τ

Product range

The KSV NIMA ISR can be equipped with either a KSV NIMA Langmuir Trough (or Liquid-Liquid Trough) for simultaneous control of the film packing density or a Low Volume Measurement cell to work with small interfacial areas and reduced subphase volumes.

Both systems enable surface pressure measurement thanks to the integrated highly sensitive Wilhelmy balance. The Langmuir Trough and the Low Volume Measurement Cell are divided into an upper and lower compartment, which can be used to study film viscoelasticity at the liquid-air or liquid-liquid interface.

All the ISR systems have designed hardware solutions for easy injection of the chemicals to enable real-time chemical interactions studies.

KSV NIMA Interfacial Shear Rheometer with KSV NIMA Langmuir Trough

Combining the KSV NIMA ISR with a Langmuir Trough or Liquid-Liquid Trough enables the compression of both soluble and insoluble films to be controlled during the measurements. As with any KSV NIMA Langmuir Trough, measurements of Isotherms, Isobars and interfacial dilatational rheology are possible.

KSV NIMA Interfacial Shear Rheometer with Low Volume Measurement Cell

When working with valuable compounds and subphases, the KSV NIMA ISR can be used with the Low Volume Measurement Cell which requires as little as a 4.7 mL of subphase. It is ideal for studying material adsorption and reaction at interfaces. A quartz glass cover minimizes liquid evaporation and reduces the influence of airflows. An integrated water circulator enables temperature control from 10 to 60 °C. Two injection ports on each end of the Cell enable easy injection of materials (e.g. proteins, enzymes) in the subphase and allow gradual subphase exchange while measuring.

KSV NIMA
Interfacial Shear Rheometer

+ KSV NIMA Langmuir Trough

KSV NIMA
Interfacial Shear Rheometer

+ Low Volume Measurement Cell

Low Volume Measurement Cell

for KSV NIMA
Interfacial Shear Rheometer

Technical specifications

 
Interfacial Shear Rheometer

Measurement

Dynamic moduli resolution (mN/m)
0.001
Frequency range (rad/s, Hz)
0.01-10, 0.0016-1.6
Strain range
3·10-4-1

Instrument Dimensions

 ISR with Langmuir Trough (L×W×H, cm)
 90.8×37.0×70.0
 ISR with Low Volume Cell (L×W×H, cm)
 19.0×37.0×70.0
*Dimensions exclude the pressure sensor Interface Unit: 15.8×20.9×27.3 cm

Low Volume Measurement Cell (Inner Dimensions)

 Lower compartment (heavy phase) (L×W×H, cm)
12.0×1.1×0.65 (volume 4.7 mL)
 Upper compartment (light phase) (L×W×H, cm)
12.0×1.96×0.6 (volume 13.9 mL)

Instrument Weight

 ISR with Langmuir Trough (kg)
 35
 ISR with Low Volume Cell (kg)
 25

System requirements

 Minimum system requirements
  • 1 GHz processor
  • 512 MB RAM
  • 40 GB hard disk drive (20 GB free)
  • 1024×768 resolution
  • 3 x USB2 Port
  • RS-232 Port (for water bath option)
 Operating system requirements
  • Windows 8 (64 bit)
  • Windows 7 (64 bit)
  • Windows Vista (32 bit)
  • Windows 10*

*Windows 10 Anniversary Update software (version 1607) is not compatible with ISR versions from 2014

Application examples

Interfacial viscosity of a protein monolayer

Graph 1 illustrates the evolution of the interfacial viscosity of a protein monolayer (lysozyme) residing between water and decane plotted as a function of time. The surface pressure of the layer is also plotted. The change in surface pressure shows the evolution of the adsorption, interfacial viscosity and the crosslinking of the protein as a viscoelastic ‘skin’ develops at the interface as a function of time. The surface pressure data complements the interfacial rheology data.

ISR Low Volume Measurement

In a KSV NIMA ISR Low Volume Measurement Cell, a 20 mg/mL solution of Lysozyme was injected in the subphase and interfacial viscolelastic properties were monitored (single frequency mode, 0.1 Hz) at an air-water interface (AW) and at an oil-water interface (OW). Graph 2 gives the storage and loss moduli obtained during both experiments. The lyzozyme injection was done at time 0s. The adsorption to the AW interface had only a slight effect on the viscoelastic properties. There was no network formation, the adsorption ended to a plateau and the viscosity dominated during the whole experiment. In the OW experiment the interfacial elasticity clearly developed faster than the interfacial viscosity and a gel point was reached after approximately 11,600 s (3.2 hours).

Phase transition in eicosanol

Graph 3 demonstrates the capability to observe a phase transition in eicosanol by measuring changes in the viscoelastic behavior as a function of surface pressure. The purple crosses show the viscous modulus (surface loss, G’’) that reaches a maximum value at a surface pressure of 5mN/m while nothing is visible on the surface pressure isotherm. The blue crosses show the elastic modulus (surface storage, G’). Both G’ and G’’ reach a constant value when the surface pressure reaches approximately 15 mN/m. The value corresponds to a phase transition in the packing of the eicosanol monolayer from tilted liquid to a non-tilted liquid phase. After the phase transition value is reached the film retains some viscous properties while the elasticity is practically zero.